Lepton number violation decays inE ₆ string model

Summary

Lepton number violation decays ℓ _i →ℓ _jγγ and ℓ _i →3ℓ _j are investigated in the framework ofE ₆ superstring model and the explicit expression for these decay rates are obtained. Relations between lepton number violation decays ℓ _i →ℓ _jγγ and ℓ _i →ℓ _jγ are established and it is shown that the relative value of these decays is independent of the details of the considered model. In the considered model we predict that BR(τ → μγγ) is large than BR(μ → eγ) in spite of the fact that τ → μγγ decay is suppressed by a factor of α_el/π, compared to the μ → eγ. Using the present experimental restrictions, the upper bound for τ → μγγ decays and lower limits for the masses of new particles are obtained. Also it is shown that rare μ → 3e decay has large BR in comparison with τ → 3μ and τ → 3e decays.